Quicksilver is another name for the element MERCURY, which is represented by the symbol Hg on the periodic table. It is a heavy, silvery-white metal that is liquid at room temperature and is the only metal that is liquid at this temperature. Quicksilver has been used in many applications throughout history, including thermometers, barometers, and other scientific instruments. It is also used in some industrial processes, such as the production of chlorine gas.